Polyunsaturated Fats Not As Heart Friendly As You Think: Study

A study located found inside dusty basement of late Ivan Frantz by Christopher Ramsden, medical investigator at US National Institutes of Health, opened a Pandora's Box into the so-called Minnesota Coronary Experiment.

The study was conducted to test whether or not reducing saturated fat will also reduce the risk of coronary heart disease and subsequent death. Between 1968 and 1973, half of more than 9,000 patients from state mental hospitals and nursing homes were kept on a diet of saturated fats from milk, cheese and beef. The other half had meals in which saturated fats were replaced with corn oil, a form of polyunsaturated fats.

The study later revealed that even though the patients on polyunsaturated diet had noticed drops in cholesterol, they became exposed to higher risk of death during the study period.

"One would expect that the more you lowered cholesterol, the better the outcome," Dr Ramsden told The New York Times.

"But in this case the opposite association was found. The greater degree of cholesterol lowering was associated with a higher, rather than lower, risk of death."

Corn oil contains linoleic acid that contains high amounts of omega-6 fatty acids that are linked to inflammation and other negative health effects. According to some experts, these effects far outweigh the cholesterol-lowering benefits.

"The benefits of choosing polyunsaturated fat over saturated fat seem a little less certain than we thought," said Lennert Veerman, a senior lecturer in the School of Public Health at the University of Queensland in an editorial in the journal BMJ where Dr. Ramsden's re-examined data study was published this week.

Dr. Ramsden and his team of researchers reanalyzed data obtained from a study conducted in Australia in 1960 by NSW University researchers. Sydney Diet Study, as it was called, had middle aged outpatients at a coronary care clinic. The analysis made by the researchers was published in 2013 and showed that saturated fats in men's diet reduced cholesterol level but they were more likely to die from a heart attack than those who consumed more saturated fat.

Dr. Veerman said that if blood cholesterol levels are not a reliable sign of heart disease risk, "then a careful review of the evidence that underpins dietary recommendations is warranted."